Updated common.ant.xml to copy pom.xml (if found) to  build/out
Added .place-holder to ensure war dir existence

Review at http://gwt-code-reviews.appspot.com/782801

Review by: rice@google.com

git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@8602 8db76d5a-ed1c-0410-87a9-c151d255dfc7
diff --git a/samples/build.xml b/samples/build.xml
index 4929690..c7bc376 100644
--- a/samples/build.xml
+++ b/samples/build.xml
@@ -61,6 +61,12 @@
     </antcall>
   </target>
 
+  <target name="source" description="Copy source to the output folder">
+    <antcall target="-do">
+      <param name="target" value="source" />
+    </antcall>
+  </target>
+  
   <target name="test" description="Test GWT">
     <antcall target="-do">
       <param name="target" value="test" />